VAC Coated Rod Bearings, A FULL engine teardown after 39,500 Miles. Look inside!

[red998]

If the bearings/bolts are done right then what is next in the equation for failure?

[thekurgan]

Originally Posted by red998

If the bearings/bolts are done right then what is next in the equation for failure?

RE-read all the oil threads and clearance threads here

lather, rinse, repeat

[thekurgan]

Originally Posted by pbonsalb

If that BMW engine builder incorrectly torqued the road bolts and cross threaded a head stud, he should be fired. Maybe he is a drunk and assembled 1% of the S65 motors and these are the ones having problems.

There seem to be many properly assembled S65 with stock bearings and stock rod bolts that have no issues.

I am curious about the BMW instructions for assembling with new rod bolts. The ones I used when doing a preventative maintenance bearing change specified torquing through the 3 stage sequence 3 times for new bolts. I thought I had seen BMW instructions for older BMW motors that did not require doing the 3 stage sequence 3 times. Maybe if you do it only once, there is some added stretch and this is what causes the problems.

Also, if ARP bolts are the answer because they get the torque perfect, do both the original and new ARPs work, because they have different torque: ARP2000 bolts should be 45 ft-lb, Custom Age 625+ is 60 ft-lb.

It seems like an assembly quality control issue; I first thought so when one of the threads here showed a piece of plastic on one of the shells.

[Sephiroth]

Originally Posted by BobS

If the ARP non stretch rod bolts, tq'd correctly, are the fix, and the OEM bolts are tq'd to tightly, it would explain why some engines go 100k-150k miles with no issues and others have issues at 8k miles or 30k miles.

If in fact the clearances are to tight i've always thought there was no way a engine would make 100k-150k miles. Something else must be going on.... maybe this is it?

I think Malek repeatedly said, per Clevite, under tq'd bolts could cause this observed wear to the bearings.

[pbonsalb]

But ARP sells some rod bolts that spec 60 lbs and some that spec 45 lbs. that is a 33% torque increase on the rod end caps that apparently does not distort the rods.

[ArthurL]

Thanks for the post, OP

[BMRLVR]

Originally Posted by pbonsalb

But ARP sells some rod bolts that spec 60 lbs and some that spec 45 lbs. that is a 33% torque increase on the rod end caps that apparently does not distort the rods.

The difference in torque spec is a result of different tensile strength of the materials the bolts are made of. The higher tensile strength fastener would require higher torque to properly tension the fastener but would also distort less as loads on the big end of the rod increased.

[C-M2]

Good info here Malek. Thanks for posting.

[nusevad]

thanks for posting malek, subscribed

[Malek@MRF]

Originally Posted by wrecklessfool

Malek,

Do you have pics of the full set of OEM bearings that came from this motor? Was the one pictured the worst looking of all of them, best looking of all of them, or somewhere in between? Reason I ask is that if the other bearings looked ok then what some other folks have said about tolerance stack up being in favor of engine longevity could also be a big part of the excellent wear on the VAC bearings. If you have pics and wouldn't mind posting the full set that would be great. If not, do you remember which cylinder this bearing was from? I'm assuming it's the top shell? Thanks.

Yes, I will take the time to post the pictures of the remaining bearings. The picture posted is of Cylinder #7, the other cylinders all look terrible as well. They all have premature wear that will lead to an eventual catastrophic failure.

I don't believe the situation with this engine is tolerance stack up. The very same engine, with the same crankshaft, same rods/caps exhibited massive wear at only 6000 miles of use with no track days or airstrip events clocked on the engine yet. I will of course verify all my findings with my micrometer and bore gauges to have definitive data for everyone after the holidays are over.

Originally Posted by leigh

Malek can you post journal sizes of the crank and bore size of the rods with bearings installed and torqued with both ARP and factory rod bolts please?

And then if you still have them, do the same thing for the original factory bearings that showed excessive wear.

I will do that for you guys 100%. I do not have the original bearings unfortunately any longer, but if the previous owner kept them, I will load them back into the connecting rods and measure all clearances with respect to this engines crankshaft.

When I take these measurements, I will re-torque these rods with OEM BMW TTY bolts, calculate bearing clearance. Secondly I will then repeat the process with the ARP bolts from this engine and calculate bearing clearance.

I have another S65 here that is torn down as well, and I will provide data from that engine as well. This second engine actually suffered rod bearing failure.

Originally Posted by SenorFunkyPants

I was just going to post the same thing...a number for a rod bearing clearance that doesn't cause accelerated bearing wear would be really interesting and useful.
Great work by MRP.

Originally Posted by 1love

I think Malek repeatedly said, per Clevite, under tq'd bolts could cause this observed wear to the bearings.

That is correct. Under torqued connecting rod bolts will cause the bearing wear at the top and bottom of the shells. Starting at 90* from the parting line in both directions over a sweep of roughly 30*. Over torqued rod bolts will create excessive crush on the bearing and will create uneven wear generally about 20-30* from the bearing parting lines.

Inadequate crush will also result in the bearing not sitting tightly enough into the rod bore, and will reduce the heat transfer ability of the bearing causing it to wear out prematurely. Think of it this way... You have an electric coil stove and you want to heat up your butter knife to make it hot. If the knife is placed gently with its own weight on the heat coil, it will take longer for the heat generated to transfer from the coil to the knife. Now if you were to press the knife onto the heat coil, you will transfer that heat faster. In the case of bearings being properly set into the connecting rod bore, this is called radial pressure.

Originally Posted by BMRLVR

The difference in torque spec is a result of different tensile strength of the materials the bolts are made of. The higher tensile strength fastener would require higher torque to properly tension the fastener but would also distort less as loads on the big end of the rod increased.

Just wanted to add for everyone else on top what was said here by BMRLVR; Try not to get confused by the different torque recommendations from ARP. Their bolts changed materials and different materials require different torque values.

The connecting rod bolt is one of the most, if not the most important set of bolts in the engine. Oversight here in any shape or form is disastrous. Think 991 Porsche GT3.

I would also like to add, the intention of this post was not to take away from all the hard work from guys like PencilGeek (a.k.a. regular_guy) and all the other contributors. In the next few days I will verify my findings and share them with everyone.

[gatorfast]

Excellent work Malek. This is a huge service to the M3 community.

[Malek@MRF]

As promised... The original rod bearings out of this engine at 6000 miles.

Images labeled from Cylinder 1-8 accordingly.

[Hujan]

What in God's name happened to Cylinder 7?

[Killerfish2012]

Originally Posted by leigh

Don't count on them all been like this there are ones with these bearings and still show wear

Do you have any links to threads supporting this claim, or any pictures? Thanks

[dj_dub]

This is an awesome post...thanks for taking the time to make this thread!

[OM VT3]

Originally Posted by Killerfish2012

Do you have any links to threads supporting this claim, or any pictures? Thanks

there are pictures but the guy who has them is currently banned and can't post them

[Helmsman]

Thanks a bunch for taking time to compile and share Malek, obviously of great interest for the E9x M3 folks.

[Killerfish2012]

Originally Posted by leigh

there are pictures but the guy who has them is currently banned and can't post them

If you know the guy and can get these pictures, it would be greatly appreciated. To me this all points to BMW spotty engine manufacturing. My '09 engine for instance is fine at 108K miles, while a new 2013 engine like this would never make it to 100K miles. The crack on the block near where the bolt went in is even further evidence of poor engine assembly quality control. Although this could have been aggravated by the pressure from the supercharger. I wonder where and how these engines were manufactured? I know that with the 335I for example, early builds like mine were all robot assembled in Germany. Later on BMW started manufacturing the cars by hand in South Africa, and when you sat in the interior, you could see just how much cost cutting had gone on, on the manufacturing side. I wonder if something similar could have happened here, were some of the engines were manufactured in house, while others got sub-contracted out.

[Killerfish2012]

Originally Posted by Malek@MRF

I have another S65 here that is torn down as well, and I will provide data from that engine as well. This second engine actually suffered rod bearing failure.

What year and mileage was this engine, and what was it's history?

[Killerfish2012]

Originally Posted by Malek@MRF

As promised... The original rod bearings out of this engine at 6000 miles.

Images labeled from Cylinder 1-8 accordingly.

Being a poor black man, certainly comes in handy at times. In May I bought my '09 M3 w/ 95K or so miles. Carfax showed it sat at the dealer for two years, and some real estate guy bought it, and drove it on the interstates for two years straight. I did a ton of maintenance to it (pushing fluids), and tracked it hard at 3 different events. Now, I'm at 108K miles, just came back from Georgia, with the jewel of a car, and I'm continuing to sign up for track days next year. My point is, that, ironically, buying cars with ultra high miles, is not just being cheap, but is actually smart, because you know for certain, the engines were assembled to spec. This stuff I see nearly every week on here with some <45K engine's bearings all chewed up, shows just how much of a dangerous gamble buying a low mileage vehicles is.

[Malek@MRF]

Originally Posted by Hujan

What in God's name happened to Cylinder 7?

Looks to be debris/dirt related during the engines assembly. The crankshaft was fully inspected during my tear down, there is nothing on the crankshaft that would have led to this. No high spots, scratches or polishing errors.

Notice how the VAC/Calico bearing on the same cylinder when assembled with a conscious effort on cleanliness and meticulous practices that it doesn't exhibit this same scratching on the bearing surface.

Originally Posted by Killerfish2012

What year and mileage was this engine, and what was it's history?

The other engine is my very own engine from my 2011 E92 M3. This engine has remained naturally aspirated and unmodified for its entire life with 5000-6000 miles oil change intervals. Engine failed from rod bearing failure at approximately 39,000 miles.

[aussiem3]

Originally Posted by Malek@MRF

Looks to be debris/dirt related during the engines assembly. The crankshaft was fully inspected during my tear down, there is nothing on the crankshaft that would have led to this. No high spots, scratches or polishing errors.

Notice how the VAC/Calico bearing on the same cylinder when assembled with a conscious effort on cleanliness and meticulous practices that it doesn't exhibit this same scratching on the bearing surface.



The other engine is my very own engine from my 2011 E92 M3. This engine has remained naturally aspirated and unmodified for its entire life with 5000-6000 miles oil change intervals. Engine failed from rod bearing failure at approximately 39,000 miles.

This information is gem. Thank you very much for posting Malek. So we don't know how many lucky ones with correctly torqued engines are out there.

You're at the mercy of BMW's automated engine build process. Who knows, even a cockroach could have entered an engine during the assembly process.